linux-kernel - [PATCH] drm/sun4i: tcon: fix false-positive uninitialized build warning

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Message-Id: <20181130160508.28230-1-anders.roxell@linaro.org>
Date:   Fri, 30 Nov 2018 17:05:08 +0100
From:   Anders Roxell <anders.roxell@...aro.org>
To:     airlied@...ux.ie, wens@...e.org
Cc:     dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Anders Roxell <anders.roxell@...aro.org>,
        Arnd Bergmann <arnd@...db.de>
Subject: [PATCH] drm/sun4i: tcon: fix false-positive uninitialized build warning

With GCC version 5 and 6, this uninitialized warning can be seen.
GCC have been fixed in newer versions.

drivers/gpu/drm/sun4i/sun4i_tcon.c: In function ‘sun4i_tcon_bind’:
drivers/gpu/drm/sun4i/sun4i_tcon.c:1091:21: warning: ‘has_lvds_alt’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  bool has_lvds_rst, has_lvds_alt, can_lvds;
                     ^~~~~~~~~~~~

Reworked the code so it covers that false positive also.

Co-developed-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Anders Roxell <anders.roxell@...aro.org>
---
 drivers/gpu/drm/sun4i/sun4i_tcon.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index 0420f5c978b9..317d4fa3429c 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -1161,20 +1161,20 @@ static int sun4i_tcon_bind(struct device *dev, struct device *master,
 		 */
 		if (tcon->quirks->has_lvds_alt) {
 			tcon->lvds_pll = devm_clk_get(dev, "lvds-alt");
-			if (IS_ERR(tcon->lvds_pll)) {
-				if (PTR_ERR(tcon->lvds_pll) == -ENOENT) {
-					has_lvds_alt = false;
-				} else {
-					dev_err(dev, "Couldn't get the LVDS PLL\n");
-					return PTR_ERR(tcon->lvds_pll);
-				}
+			ret = PTR_ERR_OR_ZERO(tcon->lvds_pll);
+			if (ret == -ENOENT) {
+				has_lvds_alt = false;
+			} else if (ret) {
+				dev_err(dev, "Couldn't get the LVDS PLL\n");
+				return ret;
 			} else {
 				has_lvds_alt = true;
 			}
+		} else  {
+			has_lvds_alt = false;
 		}
 
-		if (!has_lvds_rst ||
-		    (tcon->quirks->has_lvds_alt && !has_lvds_alt)) {
+		if (!has_lvds_rst || !has_lvds_alt) {
 			dev_warn(dev, "Missing LVDS properties, Please upgrade your DT\n");
 			dev_warn(dev, "LVDS output disabled\n");
 			can_lvds = false;
-- 
2.19.1